1. Field of the Invention
Aspects of the present invention relate to a mask for evaporation including a first division mask and a second division mask, and a method and apparatus for manufacturing the same.
2. Description of the Related Art
Generally, an organic light emitting diode (OLED) includes an organic layer interposed between a first electrode (i.e., an anode) and a second electrode (i.e., a cathode). The first electrode is a transparent electrode formed of, for example, indium tin oxide (ITO), and the second electrode is formed of a metal having a low work function, such as Ca, Li, or Al. When a forward voltage is applied to the OLED, holes emitted from the anode combine with electrons emitted from the cathode to form excitons, and while the excitons are making the transition from an excited state to a ground state, light is emitted.
The second electrode is generally formed as a reflective electrode that reflects light, while the first electrode is generally formed as a transmissive electrode that transmits light. Thus, an OLED emitting light emitted from the organic layer to the second electrode may be manufactured.
Here, the organic layer may be formed by various methods. One of the methods is an evaporation method. To manufacture an OLED display device by an evaporation method, a mask having the same pattern as a thin film to be formed is attached to a surface on which the thin film will be formed, and a material for the thin film is evaporated to form the thin film having a predetermined pattern.
Meanwhile, as a flat panel display becomes larger, such a mask also becomes larger. For example, in current manufacturers of masks, a mask corresponding to a size of a 5.5 G substrate (1320 mm×1500 mm) cannot be manufactured, and thus a division mask should be used.
Generally, such a division mask is formed by equally quartering a mask frame into lattice-type subframes, and bonding masks disposed to correspond to divided openings by welding.
However, the method of equally dividing the mask frame into the subframes and bonding the masks to the divided openings by welding leads to a shadow effect due to the subframe. Thus, it is difficult to perform uniform evaporation.